Added an extension on node's 'require' module so it can import .coffee module and added some tests to make sure it works.

lib/coffee-script.js

@@ -17,6 +17,9 @@
     Lexer = this.Lexer;
     parser = this.parser;
   }
+  require.registerExtension('.coffee', function(content) {
+    return require('coffee-script').compile(content);
+  });
   // The current CoffeeScript version number.
   exports.VERSION = '0.5.5';
   // Instantiate a Lexer for our use here.